I have the following HQL
from
com.kable.web.allotment.model.Issue i
inner join fetch i.title
inner join fetch i.title.magazine
inner join fetch i.barcodes bcs
, Wholesaler w
LEFT join fetch w.localCurrencies c
inner join fetch w.location
where
w.id = :wholesalerId
and i.title.id = :titleid
and i.distributionStatus = :status
and (
(
i.distributionDate is null
and i.onSaleDate >= TRUNC(CURRENT_DATE)
)
or i.distributionDate >= TRUNC(CURRENT_DATE)
)
and bcs.type.id = w.location.id
and (bcs.localCurrency.id = c.localCurrencyType.id OR c.localCurrencyType.id IS NULL)
and i.onSaleDate BETWEEN COALESCE(c.effectiveDate, i.onSaleDate) and COALESCE(c.expirationDate, i.onSaleDate)
order by
i.distributionDate
, i.onSaleDate
All of my previously written code is expecting to get a List<Issue> back, but with the code above, I am also getting the wholesaler and its joins. In my results, I only want Issue, Title, Magazine, and Barcodes. I am using hibernate version 4.2.18.Final. How do I only return the 1st object graph? I found something about CROSS JOIN ON but it is only for Hibernate 5 or later, and I can't switch because the project is quite large and Java dependencies.
You simply need to add an explicit SELECT i clause.
As a side note, JOIN FETCH for Wholesaler associations doesn't make sense if it's not going to be present in the result anyway
Related
I have a JPQL that looks like this:
SELECT
DISTINCT b
FROM
Book b
INNER JOIN
FETCH b.volumes as v
INNER JOIN
v.metadata as md
WHERE
b.createdAt IN (
SELECT
MAX(book.createdAt)
FROM
Book book
WHERE
book.author = ?1
)
AND md.genre IN (
?2
)
Since this has to be generated dynamically, I need to use Criteria API to add various conditions. I can get everything right except for the JOINs, because the first one is a fetch and I'm not able to chain that one with the next.
This is what I have so far:
query.distinct(true);
final Join<Book, Metadata> Metadata = root.join("volumes").join("metadata");
final Subquery<LocalDateTime> subquery = query.subquery(LocalDateTime.class);
final Root<Book> plan = subquery.from(Book.class);
subquery.where(criteriaBuilder.equal(plan.get("author"), companyId));
final Expression<LocalDateTime> createdAt = book.get("createdAt");
subquery.select(criteriaBuilder.greatest(createdAt));
predicates.add(criteriaBuilder.in(root.get("createdAt")).value(subquery));
genre.ifPresent(strings -> predicates.add(criteriaBuilder.in(metadata.get("genre")).value(strings)));
return criteriaBuilder.and(predicates.toArray(new Predicate[0]));
Any idea on how to make the first join a fetch?
There is a method for it in the Root class. Without second parameter it is inner join fetch
root.fetch("volumes")
I am currently using EFCore 1.1 (preview release) with SQL Server.
I am doing what I thought was a simple OUTER JOIN between an Order and OrderItem table.
var orders = from order in ctx.Order
join orderItem in ctx.OrderItem
on order.OrderId equals orderItem.OrderId into tmp
from oi in tmp.DefaultIfEmpty()
select new
{
order.OrderDt,
Sku = (oi == null) ? null : oi.Sku,
Qty = (oi == null) ? (int?) null : oi.Qty
};
The actual data returned is correct (I know earlier versions had issues with OUTER JOINS not working at all). However the SQL is horrible and includes every column in Order and OrderItem which is problematic considering one of them is a large XML Blob.
SELECT [order].[OrderId], [order].[OrderStatusTypeId],
[order].[OrderSummary], [order].[OrderTotal], [order].[OrderTypeId],
[order].[ParentFSPId], [order].[ParentOrderId],
[order].[PayPalECToken], [order].[PaymentFailureTypeId] ....
...[orderItem].[OrderId], [orderItem].[OrderItemType], [orderItem].[Qty],
[orderItem].[SKU] FROM [Order] AS [order] LEFT JOIN [OrderItem] AS
[orderItem] ON [order].[OrderId] = [orderItem].[OrderId] ORDER BY
[order].[OrderId]
(There are many more columns not shown here.)
On the other hand - if I make it an INNER JOIN then the SQL is as expected with only the columns in my select clause:
SELECT [order].[OrderDt], [orderItem].[SKU], [orderItem].[Qty] FROM
[Order] AS [order] INNER JOIN [OrderItem] AS [orderItem] ON
[order].[OrderId] = [orderItem].[OrderId]
I tried reverting to EFCore 1.01, but got some horrible nuget package errors and gave up with that.
Not clear whether this is an actual regression issue or an incomplete feature in EFCore. But couldn't find any further information about this elsewhere.
Edit: EFCore 2.1 has addressed a lot of issues with grouping and also N+1 type issues where a separate query is made for every child entity. Very impressed with the performance in fact.
3/14/18 - 2.1 Preview 1 of EFCore isn't recommended because the GROUP BY SQL has some issues when using OrderBy() but it's fixed in nightly builds and Preview 2.
The following applies to EF Core 1.1.0 (release).
Although shouldn't be doing such things, tried several alternative syntax queries (using navigation property instead of manual join, joining subqueries containing anonymous type projection, using let / intermediate Select, using Concat / Union to emulate left join, alternative left join syntax etc.) The result - either the same as in the post, and/or executing more than one query, and/or invalid SQL queries, and/or strange runtime exceptions like IndexOutOfRange, InvalidArgument etc.
What I can say based on tests is that most likely the problem is related to bug(s) (regression, incomplete implementation - does it really matter) in GroupJoin translation. For instance, #7003: Wrong SQL generated for query with group join on a subquery that is not present in the final projection or #6647 - Left Join (GroupJoin) always materializes elements resulting in unnecessary data pulling etc.
Until it get fixed (when?), as a (far from perfect) workaround I could suggest using the alternative left outer join syntax (from a in A from b in B.Where(b = b.Key == a.Key).DefaultIfEmpty()):
var orders = from o in ctx.Order
from oi in ctx.OrderItem.Where(oi => oi.OrderId == o.OrderId).DefaultIfEmpty()
select new
{
OrderDt = o.OrderDt,
Sku = oi.Sku,
Qty = (int?)oi.Qty
};
which produces the following SQL:
SELECT [o].[OrderDt], [t1].[Sku], [t1].[Qty]
FROM [Order] AS [o]
CROSS APPLY (
SELECT [t0].*
FROM (
SELECT NULL AS [empty]
) AS [empty0]
LEFT JOIN (
SELECT [oi0].*
FROM [OrderItem] AS [oi0]
WHERE [oi0].[OrderId] = [o].[OrderId]
) AS [t0] ON 1 = 1
) AS [t1]
As you can see, the projection is ok, but instead of LEFT JOIN it uses strange CROSS APPLY which might introduce another performance issue.
Also note that you have to use casts for value types and nothing for strings when accessing the right joined table as shown above. If you use null checks as in the original query, you'll get ArgumentNullException at runtime (yet another bug).
Using "into" will create a temporary identifier to store the results.
Reference : MDSN: into (C# Reference)
So removing the "into tmp from oi in tmp.DefaultIfEmpty()" will result in the clean sql with the three columns.
var orders = from order in ctx.Order
join orderItem in ctx.OrderItem
on order.OrderId equals orderItem.OrderId
select new
{
order.OrderDt,
Sku = (oi == null) ? null : oi.Sku,
Qty = (oi == null) ? (int?) null : oi.Qty
};
I'm trying create a SELECT with GROUP BY in Firebird but I can't have any success. How could I do this ?
Exception
Can't format message 13:896 -- message file C:\firebird.msg not found.
Dynamic SQL Error.
SQL error code = -104.
Invalid expression in the select list (not contained in either an aggregate function or the GROUP BY clause).
(49,765 sec)
trying
SELECT FA_DATA, FA_CODALUNO, FA_MATERIA, FA_TURMA, FA_QTDFALTA,
ALU_CODIGO, ALU_NOME,
M_CODIGO, M_DESCRICAO,
FT_CODIGO, FT_ANOLETIVO, FT_TURMA
FROM FALTAS Falta
INNER JOIN ALUNOS Aluno ON (Falta.FA_CODALUNO = Aluno.ALU_CODIGO)
INNER JOIN MATERIAS Materia ON (Falta.FA_MATERIA = Materia.M_CODIGO)
INNER JOIN FORMACAOTURMAS Turma ON (Falta.FA_TURMA = Turma.FT_CODIGO)
WHERE (Falta.FA_CODALUNO = 238) AND (Turma.FT_ANOLETIVO = 2015)
GROUP BY Materia.M_CODIGO
Simple use of group by in firebird,group by all columns
select * from T1 t
where t.id in
(SELECT t.id FROM T1 t
INNER JOIN T2 j ON j.id = t.jid
WHERE t.id = 1
GROUP BY t.id)
Using GROUP BY doesn't make sense in your example code. It is only useful when using aggregate functions (+ some other minor uses). In any case, Firebird requires you to specify all columns from the SELECT column list except those with aggregate functions in the GROUP BY clause.
Note that this is more restrictive than the SQL standard, which allows you to leave out functionally dependent columns (ie if you specify a primary key or unique key, you don't need to specify the other columns of that table).
You don't specify why you want to group (because it doesn't make much sense to do it with this query). Maybe instead you want to ORDER BY, or you want the first row for each M_CODIGO.
A colleague of mine has the following (apparently invalid) JPQL query:
SELECT NEW com.foobar.jpa.DonationAllocationDTOEntity(a.id, a.campaign, a.campAppeal, a.campDivision, a.divisionFund)
FROM DonationAllocation a JOIN a.donation d JOIN a.allocationType t
JOIN FETCH a.campaign
WHERE d.id = :donationId
AND (t.code = 'Pledge' OR t.code = 'MatchingPledge')
It is worth noting (for later in this message) that DonationAllocation's relationship with a Campaign entity is many-to-one, and is marked as FetchType.LAZY. My colleague's intent with this query is to (among other things) ensure that a.campaign is "inflated" (eagerly fetched).
Hibernate (obviously just one JPA implementation of several), when faced with this query, says:
query specified join fetching, but the owner of the fetched association was not present in the select list
This makes sense, as the select list contains only NEW DonationAllocationDTOEntity(), and section 4.4.5.3 of the JPA 2.0 specification says:
The association referenced by the right side of the FETCH JOIN clause must be an association or element collection that is referenced from an entity or embeddable that is returned as a result of the query.
So since there is no "entity or embeddable that is returned as a result of the query" (it's a DTO constructed using the NEW operator), it follows that there is no possible association for a FETCH JOIN to reference, and hence this query is invalid.
How, given this limitation, should one construct a JPQL query in this case such that a.campaign--passed into the constructor expression--is fetched eagerly?
I would simply select the entity and its association, and llopover the results to invoke the DTO constructor explicitely. You would have the additional advantage of compile-time checks and refactorable code:
select a from DonationAllocation a
JOIN a.donation d
JOIN a.allocationType t
JOIN FETCH a.campaign
WHERE d.id = :donationId
AND (t.code = 'Pledge' OR t.code = 'MatchingPledge')
...
for (DonationAllocation a : list) {
result.add(new DonationAllocationDTOEntity(a.id,
a.campaign,
a.campAppeal,
a.campDivision,
a.divisionFund));
}
EDIT:
This query should also select what's needed, and avoid selecting the whole DonationAllocation entity:
select a.id, a.campaign, a.campAppeal, a.campDivision, a.divisionFund
from DonationAllocation a
JOIN a.donation d
JOIN a.allocationType t
WHERE d.id = :donationId
AND (t.code = 'Pledge' OR t.code = 'MatchingPledge')
and you might just add the DTO constructor in the query if you want:
select new com.foobar.jpa.DonationAllocationDTOEntity(a.id, a.campaign, a.campAppeal, a.campDivision, a.divisionFund)
from DonationAllocation a
JOIN a.donation d
JOIN a.allocationType t
WHERE d.id = :donationId
AND (t.code = 'Pledge' OR t.code = 'MatchingPledge')
The fact the a.campaign is in the select clause should be sufficient to tell Hibernate to load the entity. At least that's how it behaves in my tests.
I am attempting to call data after joining all of my tables in a postgreSQL query.
I am getting the following error:
Error in postgresqlExecStatement(conn, statement, ...) :
RS-DBI driver: (could not Retrieve the result : ERROR: table name "place" specified more than once
)
Failed to execute SQL chunk
After referring to similar posts and online resources, I have attempted setting aliases (which only create new errors about not referring to the other tables in the FROM clause), reordering the table names (the cleanest, reordered chunk is posted below), and experimenting with UPDATE/FROM/JOIN as an alternative to SELECT/FROM/JOIN. However, I think I ultimately need to be using the SELECT clause.
SELECT *
FROM place
INNER JOIN place ON place.key = form.key
INNER JOIN form ON form.id = items.formid
INNER JOIN items ON items.recid = rec.id
INNER JOIN rec ON rec.id = sub.recid
INNER JOIN sub ON sub.id = type.subid
INNER JOIN type ON type.name = det.typeid;
You have "place" in your query twice, which is allowed but you would have to alias the second use of the table "place". Also you reference something called "det", but it's not a table or alias anywhere in your query. If you want only one place that's fine, just remove the INNER JOIN place and move your place.key = form.key to the form join or to a where clause.
If you want to place tables in their because you are trying to join the table to itself the alias the second one, but you will want to make sure that you then have a clause to join those two tables on (could be part of an on or a where)
The issue ended up being the order of table names. The code below joined everything just fine:
SELECT *
FROM place
INNER JOIN form ON place.key = form.key
INNER JOIN items ON form.id = items.formid
INNER JOIN rec ON items.recid = rec.id
INNER JOIN sub ON rec.id = sub.recid
INNER JOIN type ON sub.id = type.subid
INNER JOIN det ON type.name = det.typeid;